diff options
| author | Steven Rostedt <rostedt@goodmis.org> | 2024-08-23 04:39:06 +0300 |
|---|---|---|
| committer | Steven Rostedt (Google) <rostedt@goodmis.org> | 2024-08-26 20:54:08 +0300 |
| commit | ef2bd81d0c95616fab718738be48d7cc9b23e33d (patch) | |
| tree | 74cb377eb07f2969c6634c08eed1c4d8f22b0c6f /Documentation/trace | |
| parent | 9b7bdf6f6ece6ea888cc7d2f02c00b403b66a119 (diff) | |
| download | linux-ef2bd81d0c95616fab718738be48d7cc9b23e33d.tar.xz | |
tracing: Add option to set an instance to be the trace_printk destination
Add a option "trace_printk_dest" that will make the tracing instance the
location that trace_printk() will go to. This is useful if the
trace_printk or one of the top level tracers is too noisy and there's a
need to separate the two. Then an instance can be created, the
trace_printk can be set to go there instead, where it will not be lost in
the noise of the top level tracer.
Note, only one instance can be the destination of trace_printk at a time.
If an instance sets this flag, the instance that had it set will have it
cleared. There is always one instance that has this set. By default, that
is the top instance. This flag cannot be cleared from the top instance.
Doing so will result in an -EINVAL. The only way this flag can be cleared
from the top instance is by another instance setting it.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Vincent Donnefort <vdonnefort@google.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vineeth Pillai <vineeth@bitbyteword.org>
Cc: Beau Belgrave <beaub@linux.microsoft.com>
Cc: Alexander Graf <graf@amazon.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Ross Zwisler <zwisler@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Alexander Aring <aahringo@redhat.com>
Cc: "Luis Claudio R. Goncalves" <lgoncalv@redhat.com>
Cc: Tomas Glozar <tglozar@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Jonathan Corbet" <corbet@lwn.net>
Link: https://lore.kernel.org/20240823014019.545459018@goodmis.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Diffstat (limited to 'Documentation/trace')
| -rw-r--r-- | Documentation/trace/ftrace.rst | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/Documentation/trace/ftrace.rst b/Documentation/trace/ftrace.rst index 5aba74872ba7..4073ca48af4a 100644 --- a/Documentation/trace/ftrace.rst +++ b/Documentation/trace/ftrace.rst @@ -1186,6 +1186,18 @@ Here are the available options: trace_printk Can disable trace_printk() from writing into the buffer. + trace_printk_dest + Set to have trace_printk() and similar internal tracing functions + write into this instance. Note, only one trace instance can have + this set. By setting this flag, it clears the trace_printk_dest flag + of the instance that had it set previously. By default, the top + level trace has this set, and will get it set again if another + instance has it set then clears it. + + This flag cannot be cleared by the top level instance, as it is the + default instance. The only way the top level instance has this flag + cleared, is by it being set in another instance. + annotate It is sometimes confusing when the CPU buffers are full and one CPU buffer had a lot of events recently, thus |